In 1998, ASTM Committee D13 on Textiles launched a Proficiency
Testing Program. Designed to measure the proficiency of labs testing
to various D13 standards for fabrics, the program has been successful
in its mission and has resulted in the publication of a new D13
standard.

ASTM Committee D13 on Textiles initiated the development of the Proficiency Test Program (PTP) for Textiles after the publication of an article by Dean
Flinchbaugh in the June 1995 issue of SN. This article described
the formation of an ASTM-sponsored system of proficiency tests
for laboratories with a specific field of interest.

Proficiency testing is a procedure for examining one aspect of
a laboratorys performance. It is accomplished by comparing test
results generated between laboratories, otherwise known as interlaboratory
comparisons. A comparison of actual test results from a proficiency
study is one indication of the competence of the laboratory. Proficiency
testing is similar to, but does not have the same purpose as,
interlaboratory studies conducted to validate individual ASTM
tests.

Why a PTP?

Having an internationally recognized PTP for the field of textile
testing provides the participating laboratories with a strong
tool not only for accreditation, but also for establishing customer
confidence in their competence and test results. Prior to the
inauguration of the ASTM PTP for textiles in 1998, each lab in
the textile industry operated independently either with customers
or other ad hoc groups involved with demonstrating proficiency.
These efforts often resulted in several disjointed activities
with mediocre programs that were questioned during the accreditation
process. The comparisons of data had been inconsistent. The ASTM
PTP was designed to provide participating laboratories with a
statistical quality assurance tool that would enable them to compare
their performance in conducting test methods within their laboratories
and against other laboratories worldwide.

The initial concept for establishing an ASTM-sponsored proficiency
testing program was presented to the D13 Executive Committee in
October 1995. The Subcommittee on Inflatable Restraints, D13.20,
was instructed to champion the program. Most of the interested
laboratories were International Organization for Standardization
(ISO)/ International Electrotechnical Commission (IEC) Guide 25-accredited
and they were familiar with the requirements of a PTP. As a result,
these labs were eager to be part of a recognized proficiency testing
program. The program advisory group has since been assigned to
the jurisdiction of D13.93, the subcommittee on Statistics, as
well as the ASTM PTP staff.

The Startup

A survey, outlining the design of the proposed proficiency program,
was mailed to ASTM D13 members in April 1997. The initial response
indicated that at least 20 laboratories had participated in some
type of ad hoc proficiency or interlaboratory testing study in
the past. These same ASTM D13 member company labs were very interested
in joining an ASTM-sponsored program that involved the internationally
famous standard tests that they developed and used routinely in
their laboratories. Some of the remarks made in response to the
market survey were: [a program like] this gives management confidence
in the test results; too many labs are reporting invalid results
and dont know it; if we are to participate in the U.S. and
international market, we must be able to prove proficiency and
competence; and it is important to be accurate and have test
results that are reliable and able to be correlated to other laboratory
data involving the evaluation of textile products.

The focus of the program is to use the ASTM methods that are commonly
used to test and certify textile products. Using the critical
end use of the fabric as a starting point in designing the ASTM
PTP, the task group selected the fabric variables of construction,
air permeability, tear resistance by tongue method, strength/elongation
by the grab method, and strength/elongation by the strip method.
Yarn and sewing thread methods may be added when enough interest
is generated.

Based on requests from participants, the methods for tear resistance
by falling pendulum and fabric mass/unit area have been added
to the programs scope of testing. A proficiency testing program
on the flammability testing of textiles has been proposed, however,
samples are not available at the present time.

In the beginning, it was hoped that 12 to 15 laboratories would
participate. The first test cycle of the PTP was conducted in
October 1998. Thirty-four laboratories participated. To date,
the program currently has 70 participants of which 36 are international.
The PTP has been presented, described, and discussed during a
series of lectures in the Peoples Republic of China and it was
well received (see International Scene). Those companies who participate in the PTP program represent
domestic and foreign commercial textile testing laboratories of
which many have plant or company support facilities.

Most of the participating laboratories are accredited. Some non-accredited
laboratories participate in PTPs in order to satisfy particular
customer demands, use results as an internal quality assurance
tool and as a marketing tool. As a laboratory evolves into a position
for accreditation, participation in a proficiency test program
is typically mandatory by the accreditation body.

The Process

The ASTM documents that were used as guides in designing the program
were:

The test materials used in the PTP are supplied in-kind from ASTM
D13 member companies. The test specimens are prepared and distributed
by an accredited host laboratory. Subcommittee D13.93 decides
what fabrics will be used in the program. Representative fabric
samples are selected from a homogeneous batch roll and identified.
Homogeneous materials are considered to be those laboratory samples
that are cut from the same batch (lot) sample and selected at
random for use by the participants.

The PTP Data Report Package (DRP) containing the text instructions,
cover letter and report forms are sent to the participants with
the fabric samples for each test cycle. The PTP is conducted using
three different test samples: a light, medium, and heavy fabric.
A different sample set is distributed in February and August,
which is the test cycle schedule for this PTP.

The laboratory reports the average and standard deviation of five
determinations for each test method. All test results are submitted
directly to ASTMs proficiency testing service. A strict code
of confidentiality is maintained by ASTM. Each participating lab
is notified of their individual lab identification code number
that applies to their test results in the final statistical summary
report distributed to those participants who provided data.

All final report data appears in individual data tables by reporting
parameter. The data is also presented in graphic output for easy,
visual comparison of results. The final statistical summary report
shows the position of each laboratorys data plotted against the
others.

The test results are reported using two statistical procedures.
The fabric counts of construction are reported against an assigned
value or correct response. The sample preparation company determines
this assigned value. This value is determined by averaging several
counts through the batch rolls. The other test method results
are reported using the statistical technique of Z scores. The
criteria for the Z score is:

The data, as generated and statistically treated, shows those
participating laboratories that are capable of getting the same
answer on the batch material as well as how each laboratorys
result compares to the data generated by all participants.

Feedback from the participants is welcomed and encouraged. Procedures
for considering suggestions on program improvement are in place
within Subcommittee D13.93.

One of a Kind

At the current time, the ASTM Proficiency Testing Program for
Textiles is the only program of its kind that exists in the world.
It has proven to be more comprehensive than first thought, and
it has profound international recognition and participation.

The data generated from each PTP test cycle are made available
to the individual D13 subcommittees for their information and
use in revising or improving their ASTM standard test methods.
The data is real-world, marketplace feedback on the ASTM program
tests. The results of the PTP also aid the ASTM textile subcommittees
in their effort to validate the PTP program tests by allowing
for the development of sound precision and bias statements. As
new methods are developed for particular and specific fabric variables,
the PTP for textiles will provide valuable information and data
that can be used to support technically credible statements on
the reproducibility of the new method. The data generated from
the broad-based international participation in the PTP will help
produce credible international standard tests with known precision
for the industry worldwide.

More Concrete Results

After the PTP was established and functioning, D 6674, Standard Guide for Proficiency Test Program for Fabrics, was
written. Guidance on planning a proficiency test program, selecting
the sample fabrics to be used, the testing protocol, and the calculations
for the data to be reported are included should other ASTM D13
subcommittees endeavor to establish another PTP for fabric testing.

The guide is designed to meet the quality systems proficiency
and competence requirements of participating laboratories. The
guide follows the logic of full scale laboratory tests as described
in D 2904, Practice for Interlaboratory Testing of a Textile Test Method
that Produces Normally Distributed Data, and E 1301, Guide for Proficiency Testing by Interlaboratory Comparisons,
except its emphasis is on proficiency testing. The methods described
in the guide are applicable to methods based on the measurement
of discrete measurement data and grades or scores.

ASTM D 6674 stands as a true testimony to the success and benefits
derived by all parties associated with the ASTM Proficiency Testing
Program for Textiles.

Robert M. Holcombe is laboratory director for Safety Components
International Dunean Plant. He has been involved with testing,
quality assurance, and fabric development for 39 years. Currently
he is vice chairman for Fabrics and chairs D13.59 and D13.60.
He teaches the ASTM Technical and Professional Training Program
for Textiles, and is a lead assessor for A2LA. He is a private
consultant in the areas of textile testing and quality programs
as well as assisting laboratories in preparing for accreditation.